1. Technical Field
The present invention relates to a body of material which is ignitable to generate gas to inflate an air bag. The body is made of a plurality of layers of gas generating material which are pressed together.
2. Description of the Prior Art
U.S. Pat. No. 3,194,851 discloses a propellant grain made of a plurality of layers of gas generating material. The propellant grain is used in small arms ammunition. The outer layer is a cool burning propellant to prevent gun barrel erosion. The intermediate core of the grain is characterized as a high energy material.
U.S. Pat. No. 4,698,107 discloses a nitrogen gas generating grain suitable for inflating an air bag for a vehicle. The grain has an ignition enhancing coating. The coating is applied to the grain from a solvent-based solution or suspension. This requires that the grain be dried or cured after application of the coating.
U.S. Pat. No. 3,649,045 discloses a multi-stage pyrotechnic gas generator. Each stage has a primary pyrotechnic charge and a secondary pyrotechnic charge. The secondary pyrotechnic charge is an annular ring encompassing the primary pyrotechnic charge. The secondary pyrotechnic charge functions to provide a cooling effect on the temperature of the gas generated by the primary charge.
U.S. Pat. No. 3,880,595 discloses a gas generator for inflating a bag. The generator comprises a vessel containing alternate layers of a propellant composition and an endothermic cooling composition.